All earthquakes
0.8
very light
EARTHQUAKE DETAILS

M0.8 earthquake · 3 km North-East of Vecchiano (PI)

5 years ago · 11 Sept 2021, 07:14

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 17% of Italian events in the past year

Where

3 km North-East of VecchianoEarthquakes in the province of PisaEarthquakes in Toscana

How far away could it be felt?

A quake this small is usually not felt by people: only seismographs record it.

Statistical estimate from the Italian intensity attenuation model (INGV): actual perception depends on geology, buildings and depth. Very shallow events can be felt locally even below the threshold.

Earthquake map

22 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

0.2kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×1,995 its energy
M0this quakeM2

Each extra magnitude unit releases about 32 times more energy: an M5 is not "a bit stronger" than an M4 — it is a different league.

Energy estimated with the standard Gutenberg–Richter relation; an average lightning bolt ≈ 1 billion joules. Indicative values.

The race of the seismic waves

Two waves set off from the hypocentre: the faster P wave arrives first with a sharp jolt; the S wave carries the actual shaking.

P waves — the first sharp jolt (~6 km/s)S waves — the strongest shaking (~3.5 km/s)
t ≈ 10 s

Animation sped up ~2× compared to reality.

  • Lucca
    10 km from the epicentre
    first tremor in ~2 s
    main shaking in ~4 s
  • Viareggio
    10 km from the epicentre
    first tremor in ~3 s
    main shaking in ~4 s
  • Pisa
    14 km from the epicentre
    first tremor in ~3 s
    main shaking in ~5 s
  • Massa
    32 km from the epicentre
    first tremor in ~6 s
    main shaking in ~10 s

Theoretical times with average crustal speeds: real values vary with geology. The gap between P and S waves is what earthquake early-warning systems rely on.

How deep it was born

11 km
medium depth
1.2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with the area average (~11 km)

For the same magnitude, a shallow earthquake is felt much more than a deep one: the energy starts closer to the surface.

What kind of quake is this?

Foreshock

In hindsight it was a foreshock: 5 years ago the same area had a stronger quake (M1.9). This can only be said after the fact — it was not predictable beforehand.

1.9
The mainshock
5 km North-East of Vecchiano
5 years ago · 8 Oct 2021, 08:11
Activity in the area right now (30 km radius)
0
last 24 hours
3
last 7 days
14
last 30 days
10 before11 after
this quake
Strongest of the sequence1.9

How often does it happen here?

about every ~24 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 183 events in the last 12 years of the INGV catalogue.

An average computed on the recent past: it tells how used this area is to shaking, not when the next quake will come — earthquakes cannot be predicted.

The great earthquakes in this area's history

Almost a thousand years of catalogues: the strongest documented events within ~50 km.

19206.5
Garfagnana earthquake
7 September 1920 · 42 km from here
XCompletely destructive: most buildings are destroyed.
18466.0
Colline Pisane earthquake
14 August 1846 · 41 km from here
XCompletely destructive: most buildings are destroyed.
18375.9
Lunigiana earthquake
11 April 1837 · 43 km from here
XCompletely destructive: most buildings are destroyed.
17405.6
Garfagnana earthquake
6 March 1740 · 31 km from here
VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Livorno Hills

The epicentre lies about 26 km from Livorno Hills, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.2between 1 and 7 km deep

Faults are mapped to build better and understand the territory: knowing them says nothing about when an earthquake will occur, which remains unpredictable. Source: DISS 3.3 (INGV, CC BY 4.0).

Other quakes in the area

0.2
2 km South-East of Borgo a Mozzano
20 km North-East · 5 km
5 years ago
9 Sept 2021, 03:22
1.8
4 km North of Vecchiano
1 km North-West · 15 km
5 years ago
8 Sept 2021, 17:07
1.2
5 years ago
13 Sept 2021, 23:56
0.6
5 years ago
13 Sept 2021, 23:57
1.5
2 km South of Pietrasanta
21 km North-West · 6 km
5 years ago
14 Sept 2021, 01:26
0.8
4 km South of Borgo a Mozzano
19 km North-East · 9 km
5 years ago
7 Sept 2021, 02:36
0.6
5 years ago
7 Sept 2021, 02:12
1.4
6 km South-East of Massarosa
3 km North-East · 9 km
5 years ago
15 Sept 2021, 12:27
1.0
4 km North of Vecchiano
1 km North-West · 11 km
5 years ago
15 Sept 2021, 12:30
0.9
6 km North-East of Vecchiano
3 km North-East · 10 km
5 years ago
15 Sept 2021, 12:39

Data: INGV — National Institute of Geophysics and Volcanology (CC-BY 4.0)

Estimates computed by Meteare on INGV data (Gutenberg–Richter relation; Italian macroseismic intensity attenuation model).